This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The goal of this project is to analyze protein modifications in plants using mass spectrometry. Posttranslational modifications, such as glycosylation, phosphorylation, and acetylation, play important roles in cellular regulation. Because plants are immobile and lack neuron systems, responses to the changing environment relies on cellular regulatory mechanisms. Therefore, plants are believed to have more sophisticate posttranslational regulation systems, and thus good system for proteomic study of cellular regulation mechanisms. In this project, posttranslationally modified peptides will be enriched from plant samples and analyzed by mass spectrometry. The study will focus on glycosylation (O-Gluc-NAc) and acetylation, which are known to be important for hormone signaling and growth regulation in plants. Arabidopsis mutants for enzymes catalyzing these modification processes will be used as references in the studies.